package com.wfm.leetcode.editor.cn;
public class POne51反转字符串中的单词{
//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
        public String reverseWords(String s) {
            StringBuilder sb = trimSpaces(s);

            // 翻转字符串
            reverse(sb, 0, sb.length() - 1);

            // 翻转每个单词
            reverseEachWord(sb);

            return sb.toString();
        }

        public StringBuilder trimSpaces(String s) {
            int left = 0, right = s.length() - 1;
            // 去掉字符串开头的空白字符
            while (left <= right && s.charAt(left) == ' ') {
                ++left;
            }

            // 去掉字符串末尾的空白字符
            while (left <= right && s.charAt(right) == ' ') {
                --right;
            }

            // 将字符串间多余的空白字符去除
            StringBuilder sb = new StringBuilder();
            while (left <= right) {
                char c = s.charAt(left);

                if (c != ' ') {
                    sb.append(c);
                } else if (sb.charAt(sb.length() - 1) != ' ') {
                    sb.append(c);
                }

                ++left;
            }
            return sb;
        }

        public void reverse(StringBuilder sb, int left, int right) {
            while (left < right) {
                char tmp = sb.charAt(left);
                sb.setCharAt(left++, sb.charAt(right));
                sb.setCharAt(right--, tmp);
            }
        }

        public void reverseEachWord(StringBuilder sb) {
            int n = sb.length();
            int start = 0, end = 0;

            while (start < n) {
                // 循环至单词的末尾
                while (end < n && sb.charAt(end) != ' ') {
                    ++end;
                }
                // 翻转单词
                reverse(sb, start, end - 1);
                // 更新start，去找下一个单词
                start = end + 1;
                ++end;
            }
        }
}
//leetcode submit region end(Prohibit modification and deletion)

    public static void main(String[] args) { 
        Solution solution = new POne51反转字符串中的单词().new Solution();
    }
}